1. Field of the Invention
The present invention relates to a chemical vapor deposition apparatus and a copper film formation method using the same, and in particular, to an improved chemical vapor deposition apparatus and a copper film formation method using the same which are capable of forming a copper film having excellent physical and chemical characteristics with a high deposition rate, controlling a selective deposition and blanket deposition characteristic and obtaining an embedding characteristic of a copper film for thereby implementing a reliable copper film deposition.
2. Description of the Conventional Art
Copper having a low electrical resistivity and high EM(electromigration) durability is increasingly used as a material for an aluminum semiconductor wiring in order to overcome signal transfer delay and EM problems which occur as the semiconductor device is highly-integrated, the wiring width is decreased, and the wiring length is increased. In particular, a CVD (Chemical Vapor Deposition) method is used for obtaining a desired characteristic of a copper film. In the CVD method, as a copper source for forming a thin film, Cu(I) and Cu(II) organic metallic compounds of .beta.-diketonate group, which are represented as (hfac)Cu(VTMS)[1,1,1,5,5,5-hexafluoro-2,4-pentanedionato(vinyltrimethylsil ane)copper(I):C.sub.10 H.sub.13 O.sub.2 CuF.sub.6 Si] and Cu(hfac).sub.2 [bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)copper(II):C.sub.10 H.sub.2 O.sub.4 CuF.sub.12 ], are used. When depositing a thin film using a stable solid Cu(hfac).sub.2 as a copper source, a low growth rate and a high electrical resistivity value are obtained. In the case of liquid (hfac)Cu(VTMS), the deposition characteristic is better than that of Cu(hfac).sub.2 but it is thermally unstable, so that the material is deteriorated during its storage and evaporation. In addition, since the copper source is supplied into the reaction chamber based on a bubbler method which is directly heating the bubbler having a copper source therein, a copper source temperature and vapor pressure are fluctuated, so that the vaporized amount of a copper source is inaccurately controlled. Therefore, it is impossible to obtain a uniform deposition of the copper film.
In order to overcome the above-described problems, a new material having a stable thermal characteristic, high vapor pressure and excellent deposition characteristic is needed, so that the amount of a copper source which is supplied for a deposition operation is accurately controlled.
For adapting copper chemical vapor deposition to a multilevel wiring structure for a semiconductor device, a predetermined deposition method is needed, which has a predetermined film characteristic such as an electrical resistivity, a preferred orientation, etc., a control characteristic such as a selective and a blanket depositions for a wafer formed of a diffusion barrier, an adhesion layer, a passivation layer for preventing oxidation and contamination, etc., and a good deposition characteristic for a contact and via holes and a trench structure based on a high aspect ratio pattern.
In the conventional chemical vapor deposition method, a copper film is deposited in a temperature range of about 130.degree. C. through 450.degree. C. In such temperature range, it is very difficult to fabricate a copper film having a low electrical resistivity based on a high deposition rate. Namely, at a high temperature at which a high deposition rate is obtained, a connectivity between copper grains in thin films is deteriorated dependent on a grain growth, so that an electrical resistivity is increased, and at a lower deposition temperature, a lower resistivity copper film may be formed but a deposition rate is decreased. Therefore, it is difficult to actually adapt the above-described deposition method.
In the case of the copper film, the EM durability of the wiring portion is mainly determined by a preferred orientation of Cu(111)/Cu(200). Since the conventional chemical vapor deposition is a thermally activated process, it is difficult to obtain a copper film of a high &lt;111&gt; preferred orientation. In the deposition operation, since an electron transfer plays a role for adsorption and desorption of a copper source and its intermediate products on the surface of the wafer, a deposition characteristic of a thin film such as an electrical resistivity, so that a morphology of a thin film, a deposition rate, etc. are affected by the substrate type. Therefore, since the selective deposition or blanket deposition characteristic of a copper thin film are determined based on the material of the wafer, the temperature, the pressure, etc. Therefore, it is very difficult to set an optimum deposition condition for forming a semiconductor wiring structure because a selective deposition or a blanket deposition characteristic in accordance with a fabrication condition such as a material of the wafer, a temperature and a pressure. In addition, as the size of the semiconductor pattern is decreased, a copper film of small size grains is required for filling of the small size pattern. However, if n the conventional art, since the grain size of the thin film is large and the film structure is rough, the formation characteristic may be deteriorated, so that a predetermined problem such as a poor step coverage and microvoid formation may occur in the fine pattern filled with the copper film.
Therefore, a reliable copper film formation method is needed, which is capable of overcoming film uniformity and repeatability problems related to copper deposition due to deterioration and improper delivery of a copper precursor, depositing a copper film having a lower electrical resistivity and a &lt;111&gt; preferred orientation with a high deposition rate at a lower deposition temperature, controlling a selective and blanket depositions characteristic based on a substrate material, and obtaining a good filling characteristic and a superior step coverage for forming a copper film on a semiconductor fine pattern having a high aspect ratio.